(a) Technical Field of the Invention
The present invention relates to flip chip package technology, and in particular, a method of preparing underfill into cavity between substrate and the soldered flip chip.
(b) Description of the Prior Art
Generally, in conventional flip chip technology, after the flip chip has been mounted with the substrate, filling glue process is employed at the edge of the flip chip (1 to 2 edges) so that the liquid glue is absorbed by capillary phenomenon and the air at the other edge without fill is extracted so as to allow fill all the gap between the chip and the substrate. After that a thermal hardening process is performed.
The conventional method of glue filling is not easily employed on chip with larger surface area or with high density of protruded blocks. In the process of glue filling, void is between the chip and the substrate can be formed easily. After the filling process, the height of the filler surrounded the chip cannot be controlled easily. If the height of the filler does not reach half the height of the chips thickness, cracks on the glue body will be formed, in particular at the corner of the chip is the most serious. In addition, the conventional method can only treat the fill of a single chip and therefore the yield is low. And, the moving force as a result of capillary is limited and the capillary principle cannot be easily employed on chip of large surface area. If the density of the protruded block of chip is high the void is too small and filling is not easily. If the protruded blocks are not symmetrically distributed, the speed of the filler will be affected and the condition of filling cannot be easily controlled.
Accordingly, it is an object of the present invention to provide a method of preparing underfill for flip chip package, wherein a carrier covers a substrate and chip and the top surface of an upper heat-resistant tape and the bottom surface of a lower heat-resistant tape having the same size are formed into a elongated sealed cavity, and one end of the cavity is injected with fill and the other end is used to extract air so that the underfill is rapidly filled up the cavity between the chips and the substrate, the height of the fillers around the chip can be controlled and will not form bubble. Thus, the yield and capacity of production are high.
An aspect of the present invention is to provide a device for preparing underfill of flip chip package having a carrier, an upper heat-resistant tape, a lower heat-resistant tape to cover a substrate bonded with chips to form a covered cavity, and one end of the covered cavity being filled with an underfill and another end of the cavity being undergone extraction of air within the covered cavity, characterized in that the carrier is a hard board for fabrication which is wider than the substrate and has a slot at the center, the wide and the length of the slot are smaller than that of the substrate but wider than that of the chip on the substrate, the centers of the narrower sides of the slot are respectively provided with externally extended loop and air-extraction path and the carrier is provided with positioning holes; and the upper heat-resistant tape is a high heat resistant tape with adhesion and is adhered onto the top surface of the carrier, the slot, the loop and the air-extracting path are covered and the end terminal of the loop is provided with a filling hole, and an air-extracting hole is provided at the end terminal of the air-extracting path; and the lower heat-resistant tape is a high heat-resistant tape with adhesion and can be covered at the bottom surface of the carrier.
The foregoing object and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts.
Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.